3 - indolylmethyl - 3,4 - dihydroisoquinoline derivatives and process for their production



United States Patent Oflice 3 INDOLYLMETHYL 3,4 DIHYDROISOQUINO- LINE DERIVATIVES AND PROCESS FOR THEIR PRODUCTION John Shave], Jr., Mendham, and Harold Zinnes, Rockaway, N.J., assignors to Warner-Lambert Pharmaceutical Company, Morris Plains, N.J., a corporation of Delaware No drawing. Filed Apr. 27, 1967, Ser. No. 634,133

Int. Cl. C07d 35/34 US. Cl. 260---286 Claims ABSTRACT OF THE DISCLOSURE Compounds of structure I:

s 1 are disclosed wherein R and R are hydrogen or lower alkoxy and R is lower alkyl or aralkyl. They are prepared by rearrangement of compounds of structure V:

H (v) with treatment of one equivalent of acid. These compounds are useful as intermediates in the preparation of analgesic agents of structure Ib:

@Wwm

wherein R and R each represents hydrogen or lower alkoxy and R represents lower alkyl or aralkyl.

In the above definition for R and R lower alkoxy contains from 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy and the like. The aryl portion of aralkyl includes both monohomocyclic ring systems such as phcnyl as well as monoheterocyclic ring systems such as furyl, pyridyl and the like. The alkyl 3,524,857 Patented Aug. 18, 1970 portion of aralkyl contains from 1 to '6 carbon atoms such as methyl, propyl, isopropyl, ethyl and the like.

The compounds of this invention are useful in the production of certain indolobenzazocines such as those of the formula:

N-OHa Iii 0i 1 which may be obtained by treating the compounds of this invention with sodium and tertiary butyl alcohol in liquid ammonia followed by treatment of the resulting product with an acid such as hydrochloric acid.

The compounds of structure Ib above exhibit analgesic activities in mammals such as mice and rats and are, accordingly, useful as analgesics. In order to use these benzazocines as analgesics, they are combined with an inert pharmaceutical carrier to form dosage forms such as tablets, capsules or solutions for injection with the active ingredient being present from about 0.1 to about 1.0% by weight. These compounds are administered orally or parenterally at a dose of 1 to mg. several times daily to produce the desired analgesic effect.

The compounds of this invention are produced by treating 1-indolylmethyl-1,2,3,4-tetrahydroisoquinoline of the formula:

with palladium black in an inert solvent such as p-cymene to give a 1-indolylmethylisoquinoline of the formula:

wherein X is a halide ion.

3 4 The quaternary compound TV is then reduced to a 1- and then rearranged by dissolving in water and heating indolylmethyl-1,2-dihydroisoquinoline of the formula: on a steam bath.

5 4 We have found that if more than one equivalent of acid is employed to treat compound V, a completely different fi 3 5 type of product, having the structure VII, is obtained. RF; 1 z-Ra V- R1 8 H A/N-Ra R2 10 f N H (V) H (VII) with a suitable reducing agent such as lithium aluminum The foregoing reactions may be represented by the folhydride in an inert solvent such as tetrahydrofuran. I lowing diagram:

l H 011m N N N (III) R1 1 equiv. HO] OH N-R N R 1 Y &- R, N R H on (I) lexcess H01 lKCN CH R1 R1 NRa N N-R, \N R: R H

The compound corresponding to structure V is treated The following examples are included in order further with an equivalent of a dilute aqueous acid such as hydroto illustrate the invention. All temperatures are given in chloric acid and heated to a temperature of about 90 to degrees centigrade, and room temperature is from about 95 C. such as on a steam bath to efiect rearrangement of to C. the indolylmethyl group from the 1-position to the 3-posir0 EXAMPLE 1 tion of the isoquinoline nucleus to obtain compounds of this invention corresponding to structure I above. 00H:

The resulting compound may be isolated in the form of an acid salt such as in the form of its perchlorate. A preferred method comprises treating compound I with an r alkali metal cyanide such as sodium potassium cyanide to l give a crystalline cyano derivative corresponding to struc- \N ture VI below:

1- (indol-3-ylmethy1) -6-methoxyisoquinoline R1 6 L A mixture of 125 g. (0.43 mole) of 1,2,3,4-tetrahydro- N 1-(indol-S-ylmethyl)-6-methoxyisoquinoline, 7.2 g. of R 3 H Y palladium black, and 2500 ml. of p-cymene 1S refluxed under nitrogen with vigorous stirring for 20 hours. The (V1) contents are cooled to room temperature, and the mixture It is an essential feature of this invention that no more of palladium and crystalline product is filtered off. The than one equivalent of acid be used in the rearrangement product is dissolved away from the palladium with diof compound V to compound I. This is achieved by titratchloromethane and the filtered solution is distilled in ing the tetrahydrofuran solution of V to determine its vacuo to dryness, the last traces of dichloromethane being total alkali content and adding slightly less than one removed by distilling from some added Skellysolve C equivalent of dilute hydrochloric acid. Alternatively, the which is essentially n-heptane. The residue is triturated tetrahydrofuran solution is diluted with ether and excess with petroleum ether (30-60) to give 100.8 g. of l-(indry ethereal hydrogen chloride is added to cause precipitadol-3-ylmethyl)-6-methoxyisoquinoline, M.P. l59l60. tion of the hydrochloride salt of V. This is washed well Recrystallization from isopropyl ether gives an analytical with ether to remove excess adsorbed hydrogen chloride sample, M.P. 163164.

Analysis.-Calcd. for CIQHIGNO (percent): C, 79.14; H, 5.59; N, 9.72. Found (percent): C, 79.34; H, 5.52; N, 9.48.

Refluxing an acetone solution of 125 g. of the base with excess methyl iodide for 3 hours results in precipitation of 173 g. of the methiodide, M.P. 247-249 dec.

Analysis.--Calcd. for C H IN O (percent): C, 55.83; H, 4.45; N, 6.51. Found (percent): C, 55.53; H, 4.48; N, 6.62.

Refluxing an acetone solution of g. of the base with excess benzyl bromide for 16 hours gives 19.9 g. of the benzyl bromide salt, M.P. 2l9-222 dec.

EXAMPLE 2 O 0 Ha -OCHa 1- (indol-3-ylmethyl) -6,7-dimethoxyisoquinoline A mixture of 80 g. (0.24 mole) of 1,2,3,4-tetrahydro- 1-(indo1-3-ylmethyl)-6,7-dimethoxyisoquinoline, 7.6 g. of palladium black, and 520 ml. of p-cymene is refluxed under nitrogen with vigorous stirring for hours. The contents are cooled to room temperature, and the mixture of palladium and crystalline product is filtered off. The product is dissolved away from the palladium by stirring with hot chloroform and the filtered solution is distilled in vacuo to a residue which is recrystallized from methanol-dichloromethane to give 63 g. of 1-(indol-3-ylmethyl)-6,7-dimethoxyisoquinone, M.P. 24l-243 dec. Ultraviolet maxima at 216 (E 57,500), 237 (66,000), 268-274 (10,300), 290 sh. (8220), 313 (4100), 326 (4800) mu.

Analysis.-Calcd. for C H N O (percent): C, 75.45; H.5.70; N, 8.80. Found (percent): C, 75.56; H, 5.67; N, 9.02.

Refluxing an acetone (700 ml.) solution of 133 g. of the base with excess methyl iodide for 3 hr. resulted in precipitation of 180 g. of the methiodide, M.P. 245- 246 dec.

Refluxing an acetone (700 ml.) solution of 133 g. of the base with excess benzyl bromide for 20 hr. resulted in precipitation of 195 g. of the benzyl bromide quaternary salt, M.P. 217218.5 dec.

EXAMPLE 3 CHgO 1-cyano-3- (indol-3-ylmethyl -6-methoxy-2-methyll,2,3,4-tetrahydroisoquinoline A mixture of 87 g. (0.2 mole) of 1-(indol-3-ylrnethyl)- 6-methoxyisoquinoline methiodide, 15.2 g. (0.4 mole) of lithium aluminum hydride, and 2000 ml. of tetrahydrofurau is stirred 18 to 24 hours overnight at room temperature. The reaction mixture is hydrolyzed in the usual manner and filtered. The filtrate is concentrated on a flash evaporator (maximum temperature is 35) to a volume of 500 ml. and a 1.0 ml. sample is found by titration to contain 0.391 millequivalent of base. To 498 ml. (containing 0.1947 equivalent of base) is added 1908 ml. (0.1908 mole) of 0.1 1 N hydrochloric acid followed by 2000 ml. of water. The solution is heated on a steam bath (90) for 1 hour and allowed to cool to room temperature. The clear yellow solution is decanted from some insoluble gum, made alkaline with sodium bicarbonate, and extracted with dichloromethane. The aqueous layer is treated with excess sodium cyanide and the solid which precipitates on stirring and scratching is collected, Washed well with water, and dissolved in dichloromethane. The dried solution is evaporated to a residue which is triturated with benzene to give 31 g. of product, M.P. 152.5-154. Recrystallization from benzene gives material, M.P. 153-154.

Analysis.Calcd. for C H N O (percent): C, 76.10; H, 6.39; N, 12.68. Found (percent): C, 76.21; H, 6.49; N, 12.91.

EXAMPLE 4 'filNornou-n N H 2-benzyl-3-(indol-3-ylmethyl)-6-methoxy-3,4- dihydroisoquinolinium perchlorate A mixture of 16 g. (0.035 mole) of 2-benzyl-1-indol- 3-yl-methyl-6-methoxyisoquinolinium bromide, 4 g. (0.11 mole) of lithium aluminum hydride, and 400 ml. of tetrahydrofuran is stirred overnight at room temperature. The reaction mixture is hydrolyzed and filtered. The filtrate is concentrated on a rotary flash evaporator (maximum temperature is 35 to a volume of 250 ml. and a 1.0 ml. sample is found to contain 0.12 milliequivalent of base. To 249 ml. (containing 0.0298 equivalent) is added 2655 ml. of 0.1 N hydrochloric acid followed by 500 ml. of water. The solution is heated on a steam bath for 1 hr. and allowed to cool to room temperature. The clear yellow solution is decanted from some insoluble gum, made alkaline with sodium bicarbonate, and extracted with dichloromethane. The dichloromethane solution is extracted with several portions of 0.5 N hydrochloric acid. The acidic solution is made basic with dilute sodium hydroxide and extracted with dichloromethane. Evaporation of the dichloromethane gives 6.2 g. of solid residue. This is dissolved in ml. of methanol and a mixture of 4 ml. of 70% aqueous perchloric acid and 36 ml. of methanol is added to cause precipitation of 4.4 g. of crystalline product, M.P. l90-194 dec. Recrystallization from methanol gives an analytical sample, M.P. 192-193 dec.

Analysis.Caled. for C H ClN O (percent): C, 64.93; H, 5.24; Cl, 7.37; N, 5.82. Found (percent): C, 64.95; H, 5.27; Cl, 7.25; N, 6.07.

EXAMPLE 5 OCHQ 0 C H 1-cyano-3- (indol-3-ylmethyl)-6,7-dimethoxy- 2-methyl- 1 ,2,3,4-tetrahydroisoquinoline tain 0.223 millequivalent of base. To 97 ml. (containing 0.0212 equivalent of base) was added 212 ml. of 0.1 N hydrochloric acid followed by 238 ml. of water. The solution was heated on a steam bath (90) for 1 hr. and allowed to cool to room temperature. The clear yellow solution was decanted from some insoluble gum, made alkaline with sodium bicarbonate, and extracted with dichloromethane. The aqueous layer was treated with excess sodium cyanide and the solid which precipitated on stirring and scratching was collected, washed well with water, and dissolved in dichloromethane. The dried solution was evaporated to give 3.5 g. of crystalline product, M.P. 147-149. Recrystallization from dichloromethanemethanol gave an analytical sample, M.P. 149-150.

Analysis.-Calcd. for C H N O (percent): C, 73.10; H, 6.41; N, 11.63. Found (percent): C, 73.21; H, 6.69; N, 11.73.

We claim:

1. A compound of the formula:

q-on

wherein R is methoxy, R is hydrogen and R is lower alkyl or phenyl lower alkyl; and X is hailde or perchlorate.

2. The compound of claim 1 which is 2-benzyl-3-(indol- 3 yl methyl) 6 methoxy 3,4 dihydroisoquinolinium perchlorate.

3. A compound of the formula:

R1 CH N-Ra ( JN (VI) in an inert solvent in the presence of palladium black to obtain a compound of the formula:

Y CH

H (III) refluxing said compound with a compound of the formula R3X to obtain a compound of the formula:

X- Rt R N-R contacting said compound IV with lithium aluminum hydride at room temperature to obtain a compound of the formula:

R N-R,

N H and followed by contacting said compound V with 'no more than one equivalent of an acid at a temperature of about to C.

References Cited UNITED STATES PATENTS 2,814,625 11/ 1967 Specter 260288 3,326,923 6/1967 Shavel et a1 260288 3,370,063 2/1968 Suh 260287 X DONALD G. DAUS, Primary Examiner US. Cl. X.R. 

